1. Field
The disclosed concept relates generally to containers and, more particularly, to metal containers such as, for example, beer or beverage cans, as well as food cans. The disclosed concept also relates to cups and blanks for forming cups and containers. The disclosed concept further relates to methods and tooling for selectively forming a cup or bottom portion of a container to reduce the amount of material in the cup or bottom portion.
2. Background Information
It is generally well known to draw and iron a sheet metal blank to make a thin walled container or can body for packaging beverages (e.g., carbonated beverages; non-carbonated beverages), food or other substances. Typically, one of the initial steps in forming such containers is to form a cup. The cup is generally shorter and wider than the finished container. Accordingly, the cups are typically subjected to a variety of additional processes that further form the cup into the finished container. As shown, for example, in FIG. 1, a conventional can body 2 has thinned sidewalls 4,6 and a bottom profile 8, which includes an outwardly protruding annular ridge 10. The bottom profile 8 slopes inwardly from the annular ridge 10 to form an inwardly projecting dome portion 12. The can body 2 is formed from a blank of material 14 (e.g., without limitation, sheet metal).
There is a constant desire in the industry to reduce the gauge, and thus the amount, of material used to form such containers. However, among other disadvantages associated with the formation of containers from relatively thin gauge material, is the tendency of the container to wrinkle, particularly during redrawing and doming. Prior proposals have, in large part, focused on forming bottom profiles of various shapes that were intended to be strong and, therefore, capable of resisting buckling while enabling metal having a thinner base gauge to be used to make the can body. Thus, the conventional desire has been to maintain the material thickness in the dome and bottom profile to maintain or increase strength in this area of the can body and thereby avoid wrinkling.
Tooling for forming domed cups or can bodies has conventionally included a curved, convex punch core and a concave die core, such that a domed can body is formed from material (e.g., without limitation, a sheet metal blank) conveyed between the punch core and the die core. Typically, the punch core extends downwardly into the die core, forming the domed cup or can body. In order to maintain the thickness of the domed portion, the material is relatively lightly clamped on either side of the portion to be domed. That is, the material can move (e.g., slide) or flow toward the dome as it is formed in order to maintain the desired thickness in the bottom profile. Doming methods and apparatus are disclosed, for example and without limitation, in U.S. Pat. Nos. 4,685,322; 4,723,433; 5,024,077; 5,154,075; 5,394,727; 5,881,593; 6,070,447; and 7,124,613, which are hereby incorporated herein by reference.
There is, therefore, room for improvement in containers such as beer/beverage cans and food cans, as well as in selectively formed cups and tooling and methods for providing such cups and containers.